Pressure-Sensitive Adhesives or PSAs are substances that give the substrate, also called carrier, coated therewith an immediate tack at room temperature, which allows its instantaneous adhesion to a surface under the effect of brief slight pressure.
The substrate can be constituted of paper or a film of polymer material having one or more layers. The adhesive layer that covers the substrate may itself be covered with a protective non-sticking layer (often called a “release liner”), for example composed of a siliconized film. An option is to have a non-sticking layer or face directly existing/created on the back of the substrate. This is the common configuration when we talk about tape. Thanks to the back-side non-sticking layer, the substrate coated with the adhesive layer may be wound up without any sticking problem resulting from the contact of the back side of the substrate and the adhesive layer. For example, the substrate may be a release liner having on both sides, a non-sticking layer or face. In this configuration, the substrate is used in order to produce and transport the self-adhesive article since the substrate is coated with the adhesive layer, and the coated substrate may be wound up and unwounded. Then, after unwounding the adhesive article, a substrate bearing the adhesive layer is obtained. After application of the self-adhesive layer onto a surface to be bonded, the substrate is removed and the bonded article comprises only the adhesive layer, without any substrate. This is the common configuration when we talk about “transfer tape”. The multilayer system obtained is generally packaged by being wound up in the form of large reels up to 2 m in width and 1 m in diameter, which can be stored and transported.
Generally, PSAs are based on adhesive compositions in a solvent phase. Those solvents aim at improving mixing, dosing or pumping of those adhesives during their production but also at facilitating their coating in thin layer, which after solvent evaporation will be a self-adhesive layer. Nevertheless, the use of solvents is subjected to stricter and stricter regulations.
More recently, water-based adhesives have been developed. In this case, the problems related to solvents are solved but a problem related to the evaporation step persists. Indeed, the energy necessary to evaporate water from the coated adhesive composition is very high; thus, the process is not satisfying with regards to energy demand, therefore it is dissatisfying from an environmental point of view.
Even more recently, adhesives based on solvent-free technologies have been developed. Those adhesives are named “Hot-Melt Pressure-Sensitive Adhesives” (HMPSA). HMPSAs generally comprise a thermoplastic polymer, in particular elastomeric block copolymers, usually in combination with tackifying resins and plasticizers.
Some applications require a pressure-sensitive adhesive article that can be used to provide a bonding in wet environments, such as a wet atmosphere, like under-water. Some applications require a pressure-sensitive adhesive article that can be bonded to a wet surface.
Among such applications mention may be made of:                medical applications, such as bandage, blisters, wound dressing, electrode pads, plasters, etc        clothing applications, such as clothing dealing with wet weather or with under-water activities,        masking films, lettering, decals, graphic arts PSA films, PSA plotted articles,        building applications, especially in areas where the climate is humid, also for buildings or building parts in frequent or permanent water environment, such as bridges, roofings, wall coverings, water towers, manufacturing plants, swamp areas, water treatment centers, aquatic activity centers, bathrooms, kitchens, etc        bonding applications for transport where parts of vehicles are regularly or permanently exposed to wet environments, like for making or repairing individual cars, buses, trucks, professional vehicles, boats, ships, cargos.        transportation of gas or liquid, such as pipes.        
As wet environment, mention may be made of natural water, stagnant or flowing water, sea water, rain water, detergent aqueous composition, disinfectant aqueous composition, specifically compounded water for any purpose such as swimming-pool water, sewage water, fire extinguishing water, cooling water for any equipment or machine running with gas, oil or electricity.
Body fluids can also be considered as a wet environment since they contain a significant amount of water. Mention may be made of sweat, saliva, blood, urine, feces, and lymphatic fluids.
As a wet surface, mention may be made of skin surface, surfaces present in humid areas, such as a roof, a bathroom or a kitchen or any surface present in an area where the climate is humid.
The bonding can be a permanent or a removable bonding; it can have a high grab or a low tack; it can have a high shear resistance or not. The bonding can need to resist with the passage of time.
Some applications require a bonding characterized by a high peel strength, for example higher than 5 N/cm whereas other applications require a bonding characterized by a lower peel strength, for example comprises between 0.75 and 5 N/cm, preferably between 0.80 and 5 N/cm, more preferably between 0.90 and 1 N/cm, still more preferably between 1 and 5 N/cm.
Document U.S. Pat. No. 6,296,730 describes an adhesive composition suitable for use in an aqueous environment. The adhesive composition comprises a resin-plasticizer modified acrylonitrile-butadiene elastomer, dissolved in low-toxicity solvent.
Document U.S. Pat. No. 8,028,353 describes a foam device for use in a swimming pool. The foam comprises an adhesive layer selected from hot-melt adhesive, solvent-based adhesive, water-based adhesive or UV-cured polymer.
Document EP 1 715 015 describes a pressure sensitive adhesive composition comprising an oxyalkylene polymer containing 0.3 to 0.7 equivalent of a hydrolysable silyl group per molecule, a tackifier resin and a curing catalyst.
Document US 2010/0147443 describes an adhesive tape having at least one adhesive layer wherein at least one polymer layer comprises a foaming agent allowing the formation of a water barrier. Said adhesive layers are prepared from solvent-based polymers.
Document US 2011/0166285 describes a composition comprising 10-50% of silane-group terminated polymers, 0.5-20% by weight of (meth)acrylate block copolymers, 85-40% by weight of fillers and auxiliaries agent. Said composition is different from the composition according to the present invention. Additionally, the very high amount of fillers leads to a composition in the form of a putty, which is not the aim of the present invention.
Document WO 2005/044888 describes an adhesive molded body comprising silyl-containing polyurethane. The compositions described in document WO 2005/044888 are different from the compositions according to the present invention. Additionally, the method of bonding is different. Indeed, said molded body adheres to a surface thanks to the application of pressure which releases the uncured core of the body in order to perform the curing and the bonding simultaneously.
Document WO 2009/106699 describes a heat-cross-linkable adhesive composition based on a polyurethane comprising two alkoxysilane-type end groups.
Document EP 2 336 208 describes a heat-cross-linkable adhesive composition, said composition being based on a polyether comprising two hydrolysable alkoxysilane-type end groups.
Documents WO 2009/106699 and EP 2 336 208 do not mention or suggest that the adhesive composition can be used to provide a bonding in a wet environment.